#471 Added support for activities in RetrieveQueue.

common/dataStructures/ActivitiesFairShareWeights.cpp

common/dataStructures/ActivitiesFairShareWeights.hpp

objectstore/AlgorithmsTest.cpp

objectstore/ArchiveQueue.hpp

objectstore/CMakeLists.txt

objectstore/GarbageCollector.cpp

objectstore/GarbageCollectorTest.cpp

objectstore/RetrieveActivityCountMap.cpp

objectstore/RetrieveActivityCountMap.hpp

objectstore/RetrieveQueue.cpp

objectstore/RetrieveQueue.hpp

objectstore/RetrieveQueueAlgorithms.hpp

objectstore/RetrieveQueueShard.cpp

objectstore/RetrieveQueueShard.hpp

objectstore/RetrieveQueueTest.cpp

objectstore/RetrieveRequest.cpp

objectstore/RetrieveRequest.hpp

objectstore/Sorter.cpp

objectstore/Sorter.hpp

objectstore/cta.proto